(a) Field of the Invention
The present invention relates to a method and a system for controlling torque of a hybrid vehicle. More particularly, the present invention relates to a method and a system for controlling torque of a hybrid vehicle that calculates power and torque of each motor when the hybrid vehicle provided with two motors operates at a transient state.
(b) Description of the Related Art
Generally, a hybrid vehicle is a vehicle which uses an engine and a motor as power source. The hybrid vehicle may be provided with one motor and one engine, but the hybrid vehicle provided with two motors and one engine is increasingly more popular in today's market. In this case, a first motor is used for controlling engine speed and a second motor is used for compensating engine torque according to the engine speed controlled by the first motor and generating demand torque.
A control portion of the hybrid vehicle determines target driving points of the engine and the first and second motors by using vehicle's speed, the demand torque, and the state of charge (SOC). However, such target driving points of the engine and each motor are determined under the assumption that the hybrid vehicle operates at a steady state. Therefore, when a hybrid vehicle operates at a transient state, actual driving points of the engine and each motor differs from the target driving points and logic for determining driving points of the engine and each motor at the transient state may be necessary.
In order to determine the driving points of each motor at the transient state, a priority order is necessary. That is, if the driving points of two motors at the transient state are simultaneously determined, a large error may occur. Therefore, after the driving point of one motor is determined, the driving point of the other motor is determined by using the driving point of just the one motor.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.